SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34b1c646e693ba10c3162042add78efab1e681b61a06382fcbc92b46431a86b3' 
  AND token = 'kfKlWLblJu5R39VN3TVV8j0TpA/VJwvhuxSdrDKjyuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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