SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cdc4f99d57815ef4227c5146130af96e83cf03a6ee6a798454d15718966bd8e' 
  AND token = 'hH/vKfuD/v0PiY0Bop5i/i8aLCgamgGwqxqrFVZORsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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