SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52abbb0caeb7a50918a64c773627ddb21457629f4b4fd7a2fc3565f2dbb6fe81' 
  AND token = 'moFPM8BxSOKSf/3RGX4T6SB13lctppknUgSu0GhPU74=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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