SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a67f5297019505926700060c9ac7136a8a0e25ff18ae1107bff38455bdadcb8b' 
  AND token = 'n+KSaqf4lnADRIzVKHicODok8JBUdFSFvPe6S84IG9o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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