SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c74dc31cee0a4714ef2b80706560c15eeb243843aa223da007a758c63905872' 
  AND token = 'Z6g/PHMlvmaD1WmWHA7hC6+8l8qlP1A+4tgRLKQorMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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