SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '312186dab3c939dc614dcb1679a05b3a87f387d7c94af8e7c0c7d9c0f828148b' 
  AND token = 'W/Gh5EYfDCJhJgzU0+gvjaKYg0t//eIEFjET9Lbt+fQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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