SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '951a29518c542fa6dd869401478a35f4e1f3520b30bc8b17556c3259d43deb40' 
  AND token = '14KwEnrlqFw9YrpbT+XUCQKGTe7C2/IHPDmKWRp76aY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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