SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e203b4283fb632af831a4785cfc70a41443ffb60ec53f7e20c81d61acb827f04' 
  AND token = 'mMj8Tlgslwtzl+NKfDcwd2d089LANZrDkSWSt45RTsM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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