SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9891e3c1716613cd02d844b3601d868de8980f6185e0549a982dd48031790a14' 
  AND token = 'SmqORIbt2JHwPmA3DluPgVJV6yB5Jjj8WmwvoiFpN8o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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