SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bc26dfaa53a21659e31dabbb4f33866931444dcff830498040de346e211d331' 
  AND token = 'nxdIbyY6hoBqTOSZvxayPSnksNtiO5lorvaJsFPZfLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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