SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe3256846e46a419ee746a7398d0d9ba96e7eb223329eac809c34c8cb4d4de38' 
  AND token = '7m1U0jTztltMQN0xHd7U4xonIS3kljaOr/LmbOF7CWk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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