SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71b6c6dfcbf0ad01a28a1e334d6253679ec55ba005f404c0d64ed2e79dc78a7b' 
  AND token = 'iSeHe07jFhSiCsb39dLHQmT3yBJWugpoa5z7Ym5IkYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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