SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45918f54502bbcc8f09b775cdcfc06350c1194639e4c767d04053985d184e48a' 
  AND token = '6vZpSqGSWmNpuknItvqDAVu+2Yjq57Fr/VDLpLHNUQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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