SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96de87325b12d187867ad8369c1599fad790a02a4ad56c9ab34723a81e8ddb62' 
  AND token = 'aXlKrSpVx+sQiCLm7pnj2PvZW7nY7WZrVVQBvXfZnjc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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