SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c4ef0c52076b91020d7d2db16cc422c996aec35f64541f10257af999cbfabe1' 
  AND token = 'Idut2AvH+Y3vHrA4/Nj/IlrXZaoELJEflBDxQ9dhnqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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