SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdb42a90350875005a0b9dfe5f123f7f24d8869392011b1a9b1ecab1e2ede454' 
  AND token = 'zs6vUTzMqD+HPC+rF8ZVVlBwsm8Pb7d6PgX1URJyk8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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