SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '760ee824ea98f90fa116101fc7b20869822eb8c98bf969118b60f01ef5c3b379' 
  AND token = 'pyIGikF4kSj0gFhTPM58KRlgEubR+Jtubg3Wyas+QC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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