SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a48087bba049a84d235f57c4e05df476f10ef80ac1c0d87891544a59ec49f816' 
  AND token = 'jCmpVauHdZW3T3G8o+j6AntgyF198LdCKscqlXAtiGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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