SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e5d028031cf893f1a00619022185f8872f51a160f3451e1c17560c554f73970' 
  AND token = 'PuYM5PMTh0SSOJRlYDZKc5/5KsTMPci+v/EdrtnhT28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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