SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a83702913efaf7c1429966e1b8884769ff1172a6e75e4218cadc26cef0aafc2f' 
  AND token = 'SNGTMl85NhVZC17i5PHfOM+p0gAyj5HqWCtrSiDxNqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}