SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b875e312fa6fabd4643f645deb7c78c5bba57c56dc4a6f29999175df2f16a959' 
  AND token = 'ZnGiSXkHhSDk8QaiHA/BSULxx21ENwrp8H6Le0lDeO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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