SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf89eefc893a00016ec7eb94e937da2025297d091091121cd39b9b4eee756b85' 
  AND token = 'XxbMeKyc+8+GzVIfwMkWCdDivGISUrcGFAmHF2YZWzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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