SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fffa2783c0dbcab8db521508831b7bc88e72abf82871c7edc73f50f9ccd3ca05' 
  AND token = 'B8L86Kw4QQ7zEzZ6Ck0R7JhDyuZf8wyRvnBI9GOQwEc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}