SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3b345cc03369ee6663f995bdc4209d77a8dec5be6955fa7d5958cb5ee08d028' 
  AND token = 'yPDul80V6HlCDmcy/Kjqzx9ukw9GSgHzpUnibxTJZBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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