SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e917ea78facfc4d82b140f8476ff98bd3b39e4ed5c95d95461cb294973e6d1ea' 
  AND token = '6Q21qTFDu0uxBHJmpJuWzAuBQmG+qaJmt71qwRJGRtg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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