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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21f257b4ba43a7e4176b72805de5a13f6f533f351cc57b0c9ac0325fdc3424c9' 
  AND token = 'dSBST0umsfPUXm04oaZDMwxA4bHWEDiBw1Fb3CThhK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}