SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7286aab9bb57c7f33998139625c0f5bc8b71af5b603e9b2fb3912af763892d75' 
  AND token = '41q87Mi2GJ3LqLAPfAwm2JUEqzVZu+L/Hmj1KdiqWkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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