SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ed3da8229fe72334de15d1cdf282e60105311bf9324aac0a2a1f0903270bf58d' 
  AND token = 'mxgVKDDuOxTDUhBJu4NEL5maIp/6ZgQwfTCy8Lq2Q3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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