SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92cef44874762692cba0c4288f9a96a66189ab1c498ad423a893273ed42789b0' 
  AND token = 'epKNeSwLTHcTXEh7dSapqeOmbwTWMgbh3ZCqdz3/dCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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