SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '250475524579a5d02d0e9a5881de0331db9767374636c213637af6429391b68a' 
  AND token = 'FJlkHd+mcbHPZmQG8vI60OpCYsxH1nk42r4N+a8aNFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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