SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42a033a31b00195edf76dbaf5709f4eb30c6b629714253ca13de1a16dc814f38' 
  AND token = 'fnSRCJoGsG4XvxdPGH6rxDMS1pgVUAKN732TflcZsnY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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