SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c508e423d8603422dd70e51510131bf55fdf85782f5aef9f99edc4236efb231' 
  AND token = 'w4zKaOvwjQ1e889aj1Zd0V43fP/XO7NFAQAzShW8zIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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