SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fed641bf930138a06290ac3fc5a95b8b23ed56b0b420538ff66079d9ede0cbc' 
  AND token = 'tFBqb36z5cyuZ0Fp4y/n5ifRiWLTEx7dN7+vzeviPZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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