SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c1ed1c4cd6017173aa9added7b91b0cb4fd2ce9e3ceca015ca7cebc478becdb' 
  AND token = 'A9EZJkoEHj8rHK7E7ICxNs/sc9tcEorf/lAuWA2ZIhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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