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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7c66817b36e2ed53d218a78bc83b3cb027a27c7f96f8457fc795a02ddce5c1a' 
  AND token = 'Et5moBRYM8yH0DZ1+dmqxRDpPAmmF0QdLf4STv9y2g4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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