SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5516076fc64b4cf0c1514d0d31827084a183ee94dcb535800a4363699f962097' 
  AND token = 'LnZP1uWPA5cE3lfHxN1LF1rdmrqHfdsb9G/rFbXMrBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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