SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4d683bf2bdcd0f31854cfdd239261235336cd64428c57df581433308779ddbd' 
  AND token = 'kkUbzw2Hy19tq2njqbAbtyanqkMLMJCNynibAsQgtCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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