SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ad955e9a5948d4bb4fe009a85831c0b7e2cf33960fc77d640f69c2069646d2f' 
  AND token = 'j8qnZxhCmLPfGYrh4H5VlRY+wJnd/xxkqHZAPYN1Rto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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