SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b962eaec1ed74b9157cab9f76d74ab72c6421b2450faa4c1b6ab3c5edfdd67c0' 
  AND token = 'fDQRaivq4kjnXK3uetGMP7HkYlcyHAVOI7JDxJkMfIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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