SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fb2d0adc858e30bec871070c554940ddafe650527176ffd4841176be85a2d1a' 
  AND token = '8VS+nLEujbfTuleZDrXBQL1zWABmtOuw8swT9KDgq8k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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