SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c28ad8b116012f2e68521a0044cf3375645640e4838e9fab76ec21daf6aa7ed' 
  AND token = 'cLFMede9tPsAlTO6FulsJmiEUDaF1UE8IixXA/8hCbc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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