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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02337024ddf327e2f497a7249212d21db65d6e4389afc5dd3ddda989886f72aa' 
  AND token = '0UgMC80DgzoUsy3qfGDyRYq6CgVW8GLP+qpktxQX2Ts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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