SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb9f1cb2335a58c14b75a53332984e19bef5d19e0a6ff3ee50105dfcd6620a8a' 
  AND token = 'eq8UJrQgRo+JuKvMXcyt1xCfk6QL78DiGFxrqKyeD2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}