SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5cab34df957b15afd8f3ff9a754496c208bc32d45a812b7e375d46056083269' 
  AND token = 'CePkHR+7ezKmi5TzY9FVk97WsvRw6+qbpCmslbVb2no=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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