SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79a6c7d81aa339521054977dc1483f48bfe9ccbfe99bf0306fcc380418536be6' 
  AND token = 'tIyH/zSZfkEgP5+CdtjUA9AN1POIoYOfF5SmvjJtC54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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