SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e2621fc131a963a0b5119473ef580473f7961241f7d7116c9f8039234ecec30' 
  AND token = '5BcVDk6DTJRh0owVHhytIvIZfTDaLxQGgNsDioULnfM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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