SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3993dfc244b006ac985bf2a8130d727279b26541504151d6a285cf3669255a72' 
  AND token = 'NOqnOLsbBfQU/65ZsIAIgbZmT4GtsiXAktVAvFXPrl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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