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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '221db7b75197446b8af0fc7fd940f09468d1cc28ccf69d77ef891dfefd849bd4' 
  AND token = '0jPhj5Qbofcq2cQ/oJIOWR4bCCgvCje7OuJcsNKp6p8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}