SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe08a1483ccb87f0e9c4f40464676719daf253f70def47a0a099e0e65fe4878e' 
  AND token = '0i+1rX/+hN2TyWg2s7MCTiiSjmfXwJ4pbqzyVTihswY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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