SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b141c3b0c25a7256b269b8bc3fb302f4224814f699216d88cfb6667a2e9b307d' 
  AND token = 'tayC7Mk8i4s5TMjmaXfL997A8eK8a55CQsjtSFvRfqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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