SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f7a3451d361f15b2e9d57721d31986038e70494180a135bbb468750dded9df3' 
  AND token = 'hPR8LvHMX8xxPh90BwBslb4loRpwzfiKFfraduBG1K0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00085

JSON explain

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