SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6968c990073baf9af0fdfab9f567051795218d252e61925a7f1f6fb543bb5c43' 
  AND token = 'f3ZoUdus2WGsnpAgf4lw6Wo+tFBndUJF5Em+vTkB9sc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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