SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1613324cc5f6e0352e4d94951817b46e6bfc9e149a787ce7d072e14016c9ad1f' 
  AND token = '4PlfuUIKJJfrTKhxtUpuYewxPYLh7UMoXToLcrohGv0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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