SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e91d0778a99a67a0003ff845af28b7836766f65b992afb690b43b260a1b5c44' 
  AND token = '8ioxUNHDLyt4g9KgypMeR/vMezuXll3a50TddoTOudY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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