SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00338a891b1e5e03c74f5af075a771c0193061ca487f030c805c65f40ba952f3' 
  AND token = 'p6xdQ1i2FmmdEvvQUR7Wva2eHlJ4ZT1PpI5NBpQg51o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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