SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3d902a54ca1901f67fb6be3315196f5018876805f50231908c67b3d9c9dda09' 
  AND token = 'sRDrRdt6HTEg2ewXdR2lidyaDrL2PvS35diw/si50pg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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