SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7576a1ccd48383b025c6023eecde2e15e67b7c60b756106b211c86270557c2b4' 
  AND token = '+RubAc+W9hjq6iTY+qbyfWjK6UExjyz2SlnN8MUXcCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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