SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5bd7cbbd4eb70735f079fadb2c6aa9bbff98544532e34dcdd674ec68c7aa5c7' 
  AND token = 'Krv6hpAE4/E2JuDAgVfnWSK75ow6RILbC0jo42qrNzs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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